Various types of flow meters exist for downhole applications and for use with electric submersible pumps (ESP) in particular. Electromagnetic flow meters have been used on the production tubing or the surface tubing leading from the discharge of an ESP as illustrated in U.S. Pat. No. 7,258,164. Variable orifice valves with pressure sensors on opposed sides of the variable orifice have been used to detect flows in a multi-zone wellbore as illustrated in U.S. Pat. No. 6,860,325. Multiphase flow meters have been used with an ESP in combination with artificial neural networks as described in U.S. application Ser. No. 12/133,704 filed Jun. 8, 2008. Venturi meters for multi-phase flow as part of a tubular string are offered by Baker Hughes Production Quest under the SureFlo-FB, SureFlo-In-Form and the Sure Flo-V product lines. Other flow measurement device that use the venturi principle for strings extending downhole are illustrated in U.S. Pat. Nos. 7,107,860; 5,736,650 (assembly inserted in a drill stem test string); U.S. Pat. Nos. 5,693,891; 6,935,189 (multi-phase venturi flow meter); U.S. application Ser. No. 12/127,232 filed May 27, 2008 having a tile of Method of Measuring Multi-Phase Flow shows the use of a two stage flow meter; and SPE 110319 entitled Inverted Venturi: Optimizing Recovery Through Flow Measurement shows creation of a venturi meter by increasing the pipe diameter as opposed to an internal constriction that is more commonly used in venturi meters.
Also relevant to downhole flow measurement using venturi or Pitot principles or others are: US Applications 2007/0193373; 2003/0192689; 2006/0196674; 2003/0010135; U.S. Pat. Nos. 4,839,644; 4,928,758; 6,755,247 and EP 0235032; WO 8902066.
Typical ESP installations involve a motor supported below a pump with an enclosure (typically a sensor system) that is cylindrically shaped that is in turn supported below the motor and is no larger than the motor. A power cable runs from the surface to the motor and via the Y point on the bottom of the motor to the enclosure, known as a gauge, has sensors in it to track the performance of the ESP motor among other functions. The data accumulated in the gauge is communicated to the surface through the power cable that is connected to the ESP motor. Normally the data is transmitted as a direct current signal on the neutral Y point of the power cable that powers the motor with alternating current. Instrumentation on the surface (chokes or capacitors) to form a Y point to discriminate between the data signal and the power feed to the motor so that the data can be interpreted at the surface in real time. The power cable is typically run to the surface without connections or splices downhole for greater reliability where data is decoded and fed into a surface control system. Transposition splices may occur to help balance power for flat cable configurations.
The present invention uses the wellbore casing as part of the venturi device that is supported below the ESP motor and located below in the inlet side of the ESP. The gauge can receive an exterior sleeve to create the venturi device within the casing. The gauge needs only minor modifications to collect the needed pressure drop data and communicate it to the power cable for the ESP for transmission to the surface. These and other features of the present invention will be more apparent to those skilled in the art from a review of the detailed description of the preferred embodiment and the associated drawings while recognizing that the appending claims define the full scope of the invention.